Piston Accumulators. gas valve end cap safety device. end cap safety device

Transcription

1 Piston Accumulators 1. Description 1.1. Function Fluids are practically incompressible and cannot therefore store pressure energy. The compressibility of a gas (nitrogen) is utilised in hydraulic accumulators for storing fluids. HYDAC piston accumulators are based on this principle. A piston accumulator consists of a fluid section and a gas section with the piston acting as the gas-proof screen. The gas section is pre-charged with nitrogen. The fluid section is connected to the hydraulic circuit so that the piston accumulator draws in fluid when the pressure increases and the gas is compressed. When the pressure drops, the compressed gas expands and forces the stored fluid into the circuit Design gas valve end cap safety device end cap piston sealing system cylinder external seal end cap safety device fluid connection HYDAC piston accumulators consist of: za cylinder with very finely machined internal surface. zend caps on the gas side and the oil side. Sealed with O-rings. za floating steel or aluminium piston which can easily be accelerated due to its low weight. za sealing system adapted to the particular application. The piston floats on two guide rings which prevent metal-to-metal contact between the piston and the accumulator wall. For use with certain aggressive or corrosive fluids, the parts coming into contact with the fluid can be nickel plated for protection, or made entirely from corrosion-resistant material. Suitable materials are also available for low temperature applications SEALING SYSTEMS Precise information about operating conditions is required in order to select the most appropriate sealing system. Important criteria for this selection are, for example: zdesign pressure, zeffective pressure differential, zswitching frequency or cycles, ztemperature fluctuation, zoperating fluid, zcleanliness of fluid (micron rating of filter), zmaintenance requirements. The sealing systems differ according to the type of piston used, each of which has its own type and arrangement of seals. The following elastomer sealing materials are available, depending on the operating conditions: znbr (acrylonitrile butadiene rubber, perbunan), zfkm (fluoro rubber, Viton ), zpur (polyurethane). 39

2 Piston design type Application Degree of contamination in the fluid 1 zfor general accumulator operation Optimized for applications with without special requirements a high level of contamination Notes Application limitations: max. piston velocity: 0.5 m/s 2 zlow-friction design zfor high piston speeds zslow movements without stick-slip effect Application limitations: max. piston velocity: 3.5 m/s 3 zlow-friction design zsimple-to-fit seals zslow movements without stick-slip effect Application limitations: max. piston velocity: 0.8 m/s 4 zlow-friction design with emergency safety features zslow movements without stick-slip effect zvery low oil transfer to the gas side Filtration: NAS Class 6 ISO Class 17/15/12 1 guide ring for pistons with Ø 150 mm 2 guide rings for pistons Ø 180 mm Application limitations: max. piston velocity: 5 m/s 40

3 1.4. Mounting position HYDAC piston accumulators operate in any position. Vertical installation is preferable with the gas-side at the top, to prevent contamination from the fluid settling on the piston seals. For accumulators with certain piston position indicators vertical installation is essential (see 1.7.). Piston accumulators with a piston diameter 355 mm must only be mounted vertically ADVANTAGES OF HYDAC PISTON ACCUMULATORS zcomplete range from I nominal volume, zhigh ratios possible between pre-charge pressure and max. working pressure, zeconomic solution using back-up gas bottles for low pressure differentials, zhigh flow rates possible; limitation: max. piston velocity, zpower savings, zhigh level of efficiency of the hydraulic installation, zgas-tight and leakage free, zno sudden discharge when seals are worn, zrequires little space, zmonitoring of the volume across the entire piston stroke or electrical limit switch. Further advantages of using the low-friction sealing system: zminimum friction, zalso suitable for low pressure differentials, zno start-up friction, zno stick-slip, zlow noise, no vibration, zhigh piston velocity up to 5 m/s for piston type 4, zimproved accumulator efficiency, zgood life expectancy of seals because of low wear, zsuitable for large temperature fluctuations, zlow maintenance requirement TECHNICAL REQUIREMENTS HYDAC piston accumulators are suitable for high flow rates. With the largest piston accumulator diameter made to date of 800 mm, a flow rate of 1000 l/s can be achieved at a piston velocity of 2 m/s Effect of sealing friction The permitted piston velocity depends on the sealing friction. Higher piston velocities are possible where there is less sealing friction. HYDAC piston accumulators of piston design type 2 allow velocities of up to 3.5 m/s Permitted velocities Gas velocity The flow velocities in the gas connection and pipe system should be limited to 30 m/s when using piston accumulators of the back-up type. Gas velocities of over 50 m/s should be avoided at all costs. Oil velocity In order to limit the pressure losses when the operating fluid is displaced, the flow velocity should not exceed 10 m/s in the adapter cross-section Function tests and fatigue tests Function tests and fatigue tests are carried out to ensure the development and continuous improvement of our piston accumulators. By subjecting the accumulators to endurance tests under realistic as well as extreme working conditions, important data can be obtained about the longterm behaviour of the components. In the case of piston accumulators, important information on gas density and the life expectancy of seals is gained from such tests. Vital data for use in accumulator sizing is gained by altering the working pressure and switching cycles Fluids The following sealing materials are suitable for the fluids listed below: NBR, resistant to: zmineral oils (HL and HLP) zfire-resistant fluids from the groups HFA, HFB and HFC zwater and seawater up to approx. 100 C NBR, not resistant to: zaromatic hydrocarbons zchlorinated hydrocarbons zamines and ketones zhydraulic fluids of type HFD FPM, resistant to: zmineral oils (HL and HLP) zhydraulic fluids of type HFD zfuels as well as aromatic and chlorinated hydrocarbons zinorganic acids (but not all, please contact our technical department) FPM, not resistant to: zketones and amines z(anhydrous) ammonia zorganic acids such as formic acid and acetic acid PUR, resistant to: zmineral oils (HL and HLP) znon-flam fluids from the HFA group PUR, not resistant to: zwater and water-glycol mixtures zalkalis zacids Temperature ranges of the seals Material HYDAC Temp. range abbrev. code long-term NBR 2-20 C C FPM 6-15 C C PUR 8-30 C C For temperatures outside these ranges, please contact our technical department for more information. There are also special grades available depending on the application Gas charging Hydraulic accumulators must only be charged with nitrogen. Never use other gases. RISK OF EXPLOSION! In principle accumulators may only be charged with nitrogen class 4.5, filtered to < 3 µm. If other gases are to be used, please contact HYDAC for advice. 41

4 1.7. PISTON POSITION INDICATORS Electrical limit switch Protruding piston rod Ultrasonic distance measurement The electrical limit switch usually monitors the max. charged condition of the piston accumulator. It can, however, also permit control functions of the attached hydraulics to be carried out over a certain stroke length. The limit switch consists of the switching rod with a permanent solenoid which is not attached to the the piston and can only achieve a limited stroke, and an anti-magnetic housing and two or more switches. These switches can be normally closed or normally open or bistable. An N/C or N/O and a bistable switch cannot be fitted simultaneously to a limit switch. Our standard limit switch is fitted with a N/C and a N/O switch. On another model, switching is carried out by inductive proximity switches. The switch is reset by a spring or the force of gravity. Vertical installation is preferable, due to the friction and possible wear and tear in the rod guide. For limit switches with a stroke of > 200 mm, vertical mounting with the gas side at the top is essential. The maximum piston velocity must not exceed 0.5 m/s over the stroke range of the limit switch. The protruding piston rod permits the position of the piston to be monitored over the whole stroke. It consists of the piston rod, which is fixed to the piston and sealed in, and what is known as the trip cam which actuates the limit switches. The position of the piston can be monitored at any point using the trip cam. This facility is used mainly to switch the pump on and off. Normally the piston rod protrudes from the accumulator on the fluid side to avoid possible points of leakage on the gas side. On the protruding piston rod version, the hydraulic connection will be on the side if the size of the end cap does not permit otherwise. The protruding piston rod functions in any mounting position. There must however be sufficient space available for the protruding piston rod to move in and out. The maximum piston velocity should not exceed 0.5 m/s. The piston position is determined by ultrasonic measurement. It is only possible to take the measurements from the fluid side because a continuous sound carrier medium is required for ultrasound. In order to eliminate false readings, the fluid must be as free of air bubbles as possible. The piston should be mounted such that no air can collect under the sensor. The measurement data is evaluated by a microprocessor and is converted into a continuous measurement signal. It is possible to pick up interim measurement results to switch system parts e.g. turn the pump on and off. The most important features of the system are: zprotection class IP 65 according to DIN zlcd display zoutputs 5 floating relay change-over switches (with 125 V, 1A rating), of which 1 is error output, and 4 are user-adjustable switching thresholds between 0 and 100 % 4-20 ma The maximum pressure for the sensor must not exceed 350 bar. 42

5 1.7.4 Cable tension measurement system Magnetic flap indication Piston position switch Using the cable tension measurement system, the position of the piston can be determined by means of a cable which is fixed to the piston. The cable is attached to a wheel which is tensioned by a spring. This wheel alters an electrical resistance via an attached rotary potentiometer during the piston movement. This resistance is converted by a transducer into an electrical signal so that it can be processed directly by a PLC system. The signal is supplied through the end cap via a pressure-tight cable gland. Alternatively various digital display units and transmitters can be connected. zdigital display unit: Supply voltage 230 V AC (or 24 V DC ) 4-channel limit comparator 4 optical coupler outputs 2 relay contact outputs 1 RS 232 interface (optionally with analogue output 4-20 ma) ztransmitter: Supply voltage 24 V DC Analog output 4-20 ma The maximum pressure must not exceed 350 bar. The piston acceleration is limited to certain values according to measurement system forces, approx g, and is limited to a max. velocity of 0.5 m/s. The measurement system is not suitable for rapid volume changes. For such loads, please contact the Technical Dept. of our head office or your local HYDAC agent. The preferred installation position is with the gas-side at the top. The cable tension measurement system can only be fitted to the gas-side of the piston accumulator. With magnetic flapper indication, the position of a piston can be determined by the colour of a set of magnetic flaps which turn as the piston moves and which are visible externally. A non-magnetic tube is fitted to the piston accumulator containing a cable, one end of which is fastened to the gas side of the piston, and the other end is attached to a magnet. Along the length of the piston accumulator a housing is also fitted which contains red/white magnetic flaps. As the magnet moves up or down its tube, the flaps turn to their opposite colour to indicate the piston's position. When the piston moves towards the gasside, the indicator moves in the direction of the oil-side. In addition, reed switches can be fitted to switch system parts or measurement scales can be fitted to the tube. The maximum piston velocity must not exceed 0.5 m/s. No more than 5 cycles per day on average should be carried out. Piston accumulators with magnetic flap indication must only be installed vertically, gas-side at the top. With the piston position switch it is possible to detect the piston position in a piston accumulator using ultrasound. The indicator can be retrofitted using a clamp. No other modification is required. It is therefore possible to install without disrupting operation. The piston position switch detects the change-over from oil to piston at which point the signal is switched off. This is the case if the piston is in the sound path or has passed it. There are three different versions available: zstandard version for hydraulic fluid with a viscosity of up to 100 cst. zspecial version for hydraulic fluid with a viscosity of up to 500 cst. zspecial version for use in explosion protected areas. Supply voltage V DC Switching output: NPN (or PNP) Detailed documentation for all piston position indicators is available on request. 43

6 2. TECHNICAL SPECIFICATIONS 2.1. EXPLANATORY NOTES Nominal volume [I] See table at Point Eff. gas volume V 0 [l] These differ slightly from the nominal volume and form the basis of the calculations of the usable volume. See Point Effective volume V [l] The volume (on the fluid side) between the working pressure p 2 and p Permitted operating temperature (fluid) -10 C C 263 K K Standard material, others on request Certificate codes Australia F 1) Brazil U3 3) Canada s1 2) China A9 CIS A6 EU member states U 1) India U3 3) Japan P New Zealand T Switzerland U Ukraine A10 USA s others on request 1) Approval required in the individual territories 2) Approval required in the individual provinces 3) Alternative certificates possible 2.2. MODEL CODE (also order example) Series Nominal volume [l] Material and piston code Piston design type (see Point 1.3.) Piston material 1 = aluminium 2 = carbon steel 3 = stainless steel Material of cylinder and end caps 1 = carbon steel 2 = carbon steel with surface protection 3 = stainless steel 6 = carbon steel (low temperature) Material of seals including piston seals 2 = NBR / PTFE compound 5 = TT-NBR / PTFE compound (low temperature) 6 = FPM / PTFE compound 8 = NBR / PUR (polyurethane) 9 = special qualities Certificate code U = PED 97/23/EC Permitted operating pressure [bar] SK / 2212 U 350 AAG VA 18 A Fluid connection Type of connection (see Table 1) Standard or specification of the type of connection (see Table 2 + 3) Size of connection (see Table 4 + 5) Gas side connection or gas valve Type of connection (see Table 1) Standard or specification of the type of connection (see Table 2 + 3) (no letter for connection type V) Size of connection (see Table 4; 5 + 6) Piston diameter 04 = 40 mm 05 = 50 mm 06 = 60 mm 08 = 80 mm 10 = 100 mm 12 = 125 mm 15 = 150 mm 18 = 180 mm 20 = 200 mm 25 = 250 mm 31 = 310 mm 35 = 355 mm 49 = 490 mm Supplementary equipment* A = electrical limit switch 35 mm stroke B = electrical limit switch 200 mm stroke C = electrical limit switch 500 mm stroke K = protruding piston rod M = magnetic flap indication S = cable tension measurement system U = ultrasonic measurement system E.. = special switch fixed or adjustable P = magnetic piston UP.. = piston position switch (e.g. UP2 = 2 position switches, UPEX = ATEX version) Safety equipment* 1 = burst disc (please give nominal pressure and temperature) 2 = gas safety valve 3 = temperature fuse Pre-charge pressure p 0 [bar] at 20 C* *if required, please state at time of ordering! 44

7 Table 1, Connection type Code letter Description A Threaded connection (female) B threaded connection (male) F Flange connection H Protruding flange K, S Combination connection / Special connection V gas valve type Table 2, Threaded connection: standard or specification Code letter Description A Thread to ISO 228 (BSP) B Thread to DIN 13 or ISO 965/1 (metric) C Thread to ANSI B1.1 (UN..-2B, seal SAE J 514) D Thread to ANSI B () Table 3, Flange connection: standard or specification Code letter Description A Flanges to DIN standards (pressure range + standard) B Flanges to ANSI B 16.5 C sae flange 3000 psi D sae flange 6000 psi E High pressure block flange (Bosch-Rexroth) PN320 F High pressure block flange (AVIT, HAVIT) Table 4, Threaded model connection sizes Type Tab.2 Code, size A B C E E F G H J K L A BSP 1/8" BSP 1/4" BSP 3/8" BSP 1/2" BSP 3/4" G 1 G1 1/4 G1 1/2 2BSP G2 1/2 3BSP B M10x1 M12x1.5 M14x1.5 M16x1.5 M18x1.5 M22x1.5 M27x2 M33x2 M42x2 M48x2 M60x2 C D 5/16-24UNF 1/16-3/8-24UNF 1/8-7/16-20UNF 1/4- Table 5, Flange model connection sizes Type Tab.3 1/2-20UNF 3/8-9/16-18UNF 1/2-3/4-16UNF 3/4-7/8-14UNF /2 1 1/16-12UNF 1 1/4-11 1/2 1 3/16-12UNF 11/2-11 1/2 1 5/16-12UNF /2 Code, size A B C E E F G H J K L A DN15 DN25 DN40 DN50 DN65 DN80 DN100 DN125 DN150 DN200 B C D E F 1/2" # 1" # 1 1/2" # 2" # 2 1/2" # 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 3" # 1/2" # 1" # 1 1/2" # 1 5/8-12UNF 2 1/2-2" # 2 1/2" # 2 1/2" 3" 3 1/2" 4" 5" DN32 DN40 DN50 DN65 DN80 DN100 DN125 DN150 DN25 Table 6, Gas valve models Code letter Description A gas valve G3/4 male, with M28x1.5/M8 B gas valve end connection M28x1.5/M8 C gas valve 1/2"-20 UNF, male, with M16x2 (ISO 10945) D gas valve M14x1.5, male, with male M16x1.5 (Minimess) e gas valve G3/4, male, with 7/8-14 UNF-VG8 F gas valve end connection M42x1.5/M12 Note: Application examples, accumulator sizing and extracts from approvals regulations on hydraulic accumulators can be found in the following catalogue section: zaccumulators No

8 3. Dimensions 3.1. Piston accumulator Diagram 1 Volume V min. - max. Series Country code U = PED 97/23/EC Permitt. operating pressure Ø D1 Ø D2 Length calculation 1) L = a + (b x V) a b [mm] [mm] [l] [bar] [mm] [mm] [kg] Weight 2) min. - max SK SK SK SK SK SK SK SK SK SK SK SK SK SK SK SK SK ) The lengths calculated are usually rounded up or down in 5 mm increments 2) Intermediate weights are possible, depending on the length/diameter required Other pressures, volumes, certificates etc possible on request Effective gas volume V 0 The gas volume V is larger than the nominal volume given in the tables in point 3.1. by the amount shown below. Piston Ø D1 Piston design type [mm] D [l]

9 3.2. piston accumulator with electrical limit switch connection for Charging and Testing Unit FPU 1m1 = Motor 1c1 = Motor contactor 1e3 = Control cut-out Mö = Solenoid switch - N/C Ms = Solenoid switch - N/O Volume 2) Series Country code U Ø D1 Gas side connection 3) Fluid side connection 4) N Additional weight A B C A B C [l] [mm] ISO228 [mm] [mm] [mm] [kg] [kg] [kg] SK ) SK ) 5 SK G 3/4 G 1 lateral SK SK BSP 3/4" SK210 SK SK210 SK G 1 G 1 1/ SK210 SK SK G SK SK SK210 SK G 1 1/4 G SK210 SK SK G 1 1/ SK210 SK350 NW SK210 SK G 1 1/ SK210 SK SK G ) Electrical limit switch is not possible for these piston sizes. 2) Volume details are examples, for others see Point ) Standard connection for back-up type, others on request 4) Others on request for further information, see Point 1.7. Table 7, Supplementary seal Piston Ø [mm] all diam. Type NBR FKM (Viton ) Part no. Part no on request Note: When ordering spare parts for the piston accumulator with electrical limit switch, the supplementary seal must be ordered in addition to the seal kit (Point 4). 47

10 4. Spare parts 4.1. Piston accumulator Piston type 1 Description Qty. Item Piston assembly 1) consisting of: Piston 1 10 Seal ring 1 50 Guide ring 2 60 Centre seal 1 70 Seal kit, complete consisting of: Seal ring 2 40 Centre seal 1 70 (Support ring) (2) (110) O-ring O-ring Seal ring O-ring Piston type 2 Piston assembly (Table 8) Piston Ø NBR FKM PUR [mm] Part no. Part no. Part no Piston Seal kit, complete (Table 9) Piston Ø NBR FKM PUR [mm] Part no. Part no. Part no Piston Piston assembly 1) consisting of: Piston 1 10 Seal ring 1 40 Guide ring 2 60 Centre seal 1 70 Seal kit, complete consisting of: Seal ring 1 40 Guide ring 2 60 Centre seal 1 70 (Support ring) (2) (110) O-ring O-ring Seal ring O-ring Piston type 3 Piston assembly consisting of: Piston 1 10 Seal ring 1 70 Guide ring 1 60 Seal kit, complete consisting of: Seal ring 1 70 Guide ring 1 60 (Support ring) (2) (110) O-ring O-ring Seal ring O-ring ) Item. 120, 180, 200 und 220 are supplied loose. Pressure resistant parts cannot be supplied as spares. Spare parts for piston type 4 are available on request. 48

11 4.2. Assembly instructions Before assembling or disassembling a piston accumulator or piston accumulator station, the system must always be depressurized. The gas and fluid side must be depressurized and the gas valve unscrewed or opened before the accumulator is disassembled. Before the end caps are removed, ensure that the piston is moving freely. This may be achieved by using a rod. Only authorised persons should repair piston accumulators where the piston is jammed. Piston accumulators with internal diameters up to 250 mm are fitted with a securing pin. This pin is to prevent the end cap being removed incorrectly. It must be taken out before removing the end cap. There may be a danger to life due to stray components. All work must only be carried out by suitably trained staff. On no account must any welding, soldering or mechanical work be carried out on the accumulator shell. Please read the Operating Manual! No CE Assembly sleeves for piston accumulators (Table 11) Piston Ø [mm] to fit the seals Type Piston to install the piston Ø [mm] (M105x2) (M110x3) (M186x3) (M190x4) When replacing seals and/or pistons, please read the Operating and Maintenance Instructions (No B). 5. NOTE The information in this brochure relates to the operating conditions and applications described. For applications or operating conditions not described, please contact the relevant technical department. Subject to technical modifications. HYDAC Technology GmbH Industriegebiet Sulzbach/Saar, Germany Tel.: +49 (0) / Fax: +49 (0) / Internet: speichertechnik@hydac.com 49

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13 1. DESCRIPTION 1.1. FUNCTION Fluids are practically incompressible and cannot therefore store pressure energy. The compressibility of a gas is utilised in hydro-pneumatic accumulators for storing fluids. HYDAC piston accumulators are based on this principle, using nitrogen as the compressible medium. The piston accumulator consists of a fluid section and a gas section with the piston acting as a gasproof screen. The gas section is pre-charged with nitrogen. The fluid section is connected to the hydraulic circuit so that the piston accumulator draws in fluid when pressure increases and the gas is compressed. When the pressure drops, the compressed gas expands and forces the stored fluid back into the circuit. HYDAC piston accumulators can be used in a wide variety of applications and are also available in different pressure grades (see following brochures: Hydraulic Piston Accumulators no. E /.. and Accumulators no. DEF /..). The available brochure shows the high pressure versions of the piston accumulator (690/800/1000 bar) with its main dimensions, materials as well as gas and fluid connections. Hydraulic Piston Accumulators High Pressure E /02.05

14 1.2. CONSTRUCTION The high pressure piston accumulator consist of: a cylinder with very finely machined internal surface. end caps on the gas side and the oil side, held in place by threads. a floating metal piston. a high pressure sealing system. The piston floats on two guide rings which prevent metal-to-metal contact between the piston and the accumulator wall. For use with certain aggressive or corrosive fluids, the parts coming into contact with the fluid can also made entirely from corrosionresistant material. Suitable materials are also available for low temperature applications SEALING SYSTEMS Precise information about operating conditions is required in order to select the most appropriate sealing system. Important criteria for this selection are, for example: design pressure effective pressure differential switching frequency or cycles temperature fluctuations operating fluid cleanliness of fluid (micron rating of filter) maintenance requirements The high pressure piston is a modified piston type 2 especially designed for high pressure applications up to 1000 bar (Filtration < 20µm absolute) MOUNTING HYDAC piston accumulators operate in any position. Vertical installation is preferable with the gas side uppermost, to prevent contamination from the fluid setting on the piston sealing. 2. TECHNICAL SPECIFICATIONS 2.1. DESIGN PRESSURE Three pressure ratings are available: 690 bar / 800 bar / 1000 bar 2.2. FLUID- AND TEMPERATURE RESISTANCE OF THE SEALS NBR/PUR -20 to 80 C mineral oil, NBR/PUR 1) water FPM/PUR -15 to 80 C mineral oil, fuels 1) modified PUR for water applications 2.3. MODEL CODE (also order example) Series Nominal volume in (l) Material and piston code Piston design type 2 Piston material 2 = carbon steel 3 = stainless steel Material of cylinder and end caps 1 = carbon steel 3 = stainless steel 6 = carbon steel (low temperature) Material of seals incl. piston 2 = NBR 5 = low temperature NBR 6 = FPM Certificate code U = PED 97/23/EC Permissible working pressure (bar) SK / 2312 U ADE - VB - 18 P - 1 Fluid connection Type of connection (see table 1) Standard or specification of the type of connection (see tables 2) Size of connection (see tables 3) Gas side connection or gas valve Type of connection (see table 1) Standard or specification of the type of connection (see table 2) (no letter if type V connection) Size of connection (see tables 3 and 4) Piston diameter 08 = 80 mm 10 = 100 mm 15 = 150 mm 18 = 180 mm Supplementary equipment M = magnetic flapper indication UP = ultrasonic measurement system E.. = special switch (fixed and adjustable) P = magnetic piston Safety devices 1 = burst disc (indicate nominal pressure and temperature) E /02.05 Please contact our technical sales department to receive more and detailed information regarding fluidand temperature resistance. There are also special grades available depending on the application. 2

15 3. DIMENSIONS Gas Port 3.1. SERIES: SK690 max. allowable working pressure: 690 bar Volume Ø D1 Ø D2 * A Weight * Carbon Stainless Carbon Stainless steel steel steel steel Litre mm mm mm mm kg kg * in accordance to PED 97/23/EC 3.2. SERIES: SK800 max. allowable working pressure: 800 bar Volume Ø D1 Ø D2 * A Weight * Carbon Stainless Carbon Stainless steel steel steel steel Litre mm mm mm mm kg kg * in accordance to PED 97/23/EC Table 1, Connection type Code Description A Threaded connection (female) K Combination connection V Gas valve type Fluid Port Table 2, Threaded connection: standard or specification Code Description A Thread to ISO 228 (BSP) B Thread to DIN 13 or ISO 965/1 (metric) C Thread to ANSI B 1.1 (UN..-2B, seal SAE J 514) D Thread to ANSI B () S Special model, e.g. autoclave connection Table 3, Threaded model connection sizes Type Code, size Tab. 2 A B C D E F G A G 1/8 G 3/4 G 3/8 G 1/2 G 3/4 G 1 G 1 1/4 B M10x1 M12x1.5 M14x1.5 M16x1.5 M18x1.5 M22x1.5 M27x2 C 5/ /8-24 7/ /2-20 9/ /4-16 7/8-14 UNF UNF UNF UNF UNF UNF UNF 1/ /8-27 1/4-18 3/8-18 1/2-14 3/ /2 D 3.3. SERIES: SK1000 max. allowable working pressure: 1000 bar Volume Ø D1 Ø D2 * A Weight * Carbon Stainless Carbon Stainless steel steel steel steel Litre mm mm mm mm kg kg * in accordance to PED 97/23/EC 4. NOTE The information in this brochure relates to the operating conditions and applications described. For applications or operating conditions not described, please contact the relevant technical department. Subject to technical modifications. Table 4, Gas valve models Code Description B Gas valve end connection M28x1.5/M8 F Gas valve end connection M42x1.5 E /

16 Piston Accumulators Series SK DESCRIPTION 1.1. FUNCTION Fluids are practically incompressible and cannot therefore store pressure energy. The compressibility of a gas (nitrogen) is utilised in hydraulic accumulators for storing fluids. HYDAC piston accumulators are based on this principle. A piston accumulator consists of a fluid section and a gas section with the piston acting as the gas-proof screen. The gas section is pre-charged with nitrogen. The fluid section is connected to the hydraulic circuit so that the piston accumulator draws in fluid when the pressure increases and the gas is compressed. When the pressure drops, the compressed gas expands and forces the stored fluid into the circuit Design gas valve end cap cylinder piston end cap fluid connection HYDAC piston accumulators consist of: za cylinder with very finely machined internal surface. zend caps on the gas side and the oil side. Sealed with O-rings. za floating steel or aluminium piston. za sealing system adapted to the particular application. The piston floats on two guide rings which prevent metal-to-metal contact between the piston and the accumulator wall. Suitable materials are also available for low temperature applications Type of mounting HYDAC can provide suitable accumulator clamps for the piston accumulator series SK280. The table at point 3 lists the appropriate clamps for each individual diameter. In order to prevent deformation of the cylinder, we recommend that the accumulators are mounted using two clamps, one at each end cap Advantages of the SK280 zoptimized production process, saving on material and manufacturing costs zreduced-weight series zreduced installation space zstandard gas valve M28x1.5 integrated into end cap (non-refillable version possible) zendurance tested (function and fatigue tests) 1.5. Design pressure zstandard 280 bar zmanufactured and tested to PED 97/23/EC higher pressures on request 1.6. Sealing system zpiston type 3: NBR/PUR ztemperature range: -30 C C others on request 1.7. Commissioning Please read the Operating Manual! zpiston accumulators No CE For further information, please turn to the section: zpiston Accumulators No E /

17 2. Technical specifications 2.1. Model code (also order example) SK280-1 / 3218 U AAD - VB Series Nominal volume [l] Material and piston code Piston design type (see Point 1.6.) Material: piston 2 = Carbon steel Material: cylinder and end caps 1 = Carbon steel Material: seals including piston seals 8 = NBR/PUR (polyurethane) Certificate code U = PED 97/23/EC Permitted operating pressure [bar] Fluid connection AAD = Threaded connection to ISO 228 size G 1/2 AAE = Threaded connection to ISO 228 size G 3/4 AAF = Threaded connection to ISO 228 size G 1 ACE = Threaded connection to SAE J 514 size 9/16-18 UNF, SAE #6 ACF = Threaded connection to SAE J 514 size 3/4-16 UNF, SAE #8 ACH = Threaded connection to SAE J 514 size 1 1/16-12 UN, SAE #12 ACK = Threaded connection to SAE J 514 size 1 5/16-12 UN, SAE #16 Gas side connection or gas valve VB = Gas valve type M28x1.5/M8 integrated into gas side end cap 000 = Non-refillable version (see drawing, Point 3.1.) on request Piston diameter 05 = 50 mm Pre-charge pressure p 0 [bar] at 20 C, must be clearly stated, if required! Special sizes and special versions on request. E /

18 3. DIMENSIONS 3.1. Type (non refillable) 3.2. Type -VB- (refillable) Nominal volume [l] D1 [mm] D2 [mm] A ±3 [mm] F to ISO 228 F to SAE J 514 Weight [kg] / UNF G 1/2 3 3/ UNF / G 3/ UN / G UN Mounting clamps 1) HRGKSM 0 R 58-61/62 ST HRGKSM 0 R 70-73/73 ST HRGKSM 0 R 92-95/96 ST HRGKSM 1 R /124 ST 1) Clamps must be mounted near the end caps in order to prevent deformation of the cylinder. For further information see the following catalogue section: Supports for Hydraulic Accumulators No NOTE The information in this brochure relates to the operating conditions and applications described. For applications and operating conditions not described, please contact the relevant technical department. Subject to technical modifications. HYDAC Technology GmbH Industriegebiet Sulzbach/Saar, Germany Tel.: +49 (0) / Fax: +49 (0) / Internet: speichertechnik@hydac.com E /

19 E /